size = int(input('请输入棋盘的大小'))
for i in range(size):
    for j in range(size):
        if i ==0 and j == 0:
            print('┏',end='')
        elif i ==0 and j== size -1:
            print('┓',end ='')
        elif i ==size-1 and j== 0:
            print('┗',end ='')
        elif i ==size -1 and j== size:
            print('┛',end ='')
        elif j==0:
            print('┠',end ='')
        elif i==size - 1:
            print('┯',end ='')
        elif j==size -1:
            print('┨',end ='')
        elif i==0:
            print('┷',end ='')
        else:
            print('┼',end='')
    print('')